Bend water susceptible to crypto
八月 06, 2013
City under federal requirement to treat water, still mulling optionsBy Hillary Borrud
Bend's surface water source is among a handful in Oregon that are susceptible to the microorganism cryptosporidium that may have sickened people in Baker City.
Bend, Baker City, Reedsport and Portland all have surface water sources that are not treated for cryptosporidium, Bend water quality manager Steve Prazak said Monday. Bend takes much of its water from Bridge Creek and Tumalo Creek, in a protected watershed in the Cascades foothills. It pumps the remainder from groundwater wells around the city.
More than 200 Oregon municipalities rely on surface water, and nearly all of them already have filtration facilities to remove parasites, said Kari Salis, technical services Region 1 manager for Oregon Drinking Water Services.
The relatively pure water and protected watersheds in Bend, Baker City, Reedsport and Portland allowed the cities to delay building water treatment facilities for decades.
The federal Safe Drinking Water Act required municipalities to begin filtering surface water in 1991. “But along with that rule, they set up exemption criteria," Salis said. Bend and three other water systems met the criteria.
However, the U.S. Environmental Protection Agency issued a new rule requiring all surface water systems to treat for cryptosporidium in 2006. A variance granted Portland allows it to avoid building a treatment plant, but the other three cities still face the requirement. Bend received an extension to October 2014 of the original 2012 federal water treatment deadline, and city councilors voted 4-3 in February to re-examine which type of treatment facility the city should use.
A membrane filter would capture not only cryptosporidium, but also debris if a forest fire spread to the watershed. However, it is more expensive than ultraviolet light treatment, which would deactivate cryptosporidium: roughly $30 million and $25 million respectively, according to city estimates in 2010. The city asked a citizen advisory committee to examine treatment options and report back with a recommendation to the City Council. City Manager Eric King wrote in an email Monday that the group might wrap up work by the end of September or October.
Tom Hickmann, Bend's engineering and infrastructure planning director, said the Bridge Creek watershed is similar to Baker City in its susceptibility to cryptosporidium contamination. “We face the very same risk they do," Hickmann said.
It is possible, but so far unconfirmed, that the cryptosporidium was introduced to the Baker City water supply by scat from mountain goats or other animals. “The bottom line is that's who carries this bug, is animals like that," Hickmann said. “Elk, deer, beavers, all of which we have in our watershed."
Unlike Baker City, Bend employees test every month for cryptosporidium in the Bridge Creek watershed. “We're not required to, but we're just doing the best management practices and our due diligence," Prazak said. A city worker collected the latest 10-liter sample early Monday and sent it overnight to a laboratory in Grants Pass.
The city began testing for the microorganism on a monthly basis in December 2005, as required by a federal drinking water treatment rule. The two-year sampling period ended in January 2008, but the city continued to test its water and found the microorganism a total of seven times since 2005.
“We did not have any hits for cryptosporidium last year," Prazak said. Nor has the city found any evidence of cryptosporidium so far this year.
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